It does not sound correct at all that the bank is prohibiting it. It is much more likely that title or the end buyers lender, if there is one, is the issue. Definately do not rely on the realtor on this issue - speak directly to title to understand the recording requirements and timeline.
When I double close and the end-buyers have a question about title and the process, I always explain it to them letting them know we jump through all the hoops with getting title insurance for each closing.
Then I give them the name and phone number of my title agent so they can take their word for it.